Gas turbines typically include a compressor section, a combustion section, and a turbine section. The compressor section pressurizes air flowing into the turbine. The pressurized air discharged from the compressor section flows into the combustion section, which is generally characterized by a plurality of combustors disposed in an annular array about the axis of the engine. Air entering each combustor is mixed with fuel and combusted. Hot gases of combustion flow from the combustion liner through a transition piece to the turbine section to drive the turbine and generate power. The turbine section typically includes a turbine rotor having a plurality of rotor disks and a plurality of turbine buckets extending radially outwardly from and being coupled to each rotor disk for rotation therewith. The turbine buckets are generally designed to capture and convert the kinetic energy of the hot gases of combustion flowing through the turbine section into usable rotational energy.
The turbine section also includes a substantially cylindrical turbine casing configured to contain the hot gases of combustion. The turbine casing typically supports a turbine shroud designed to encase or shroud the rotating components of the turbine rotor. As is generally understood, the turbine shroud may be configured as a single component forming a continuous ring around the turbine rotor or may comprise a plurality of shroud sections or blocks that, when installed around the inner circumference of the turbine casing, abut one another so as generally define a cylindrical shape surrounding the turbine rotor. A cross-sectional view of one embodiment of a portion of a conventional turbine casing 10 and turbine shroud 12 is illustrated in FIG. 1. In general, the turbine shroud 12 may be configured to be supported around the inner circumference of the turbine casing 10 so that an inner surface 14 of the turbine shroud 12 may be disposed adjacent to the tips of the rotating buckets of the turbine rotor (not shown). For instance, as shown in the illustrated embodiment, a shroud fit 16 may project from an inner surface 18 of the turbine casing 10. In such an embodiment, the turbine shroud 12 may define a corresponding slot 20 having a size and/or shape generally corresponding to the size and/or shape of the shroud fit 16 so that the turbine shroud 12 may be installed onto the shroud fit 16 and, thus, may be radially supported against the inner surface 18 of the casing 10.
Additionally, a plurality of retaining pins 22 may be installed radially between the turbine casing 10 and the turbine shroud 12 to circumferentially and/or axially retain the turbine shroud 12 relative to the turbine casing 10. In particular, the turbine casing 10 may define a plurality of retaining holes 24 configured to be generally aligned with a plurality of corresponding retaining holes 26 defined in the turbine shroud 12. Thus, a retaining pin 22 may be radially inserted through one of the retaining holes 24 defined in the turbine casing 10 and may extend into the corresponding retaining hole 26 defined in the turbine shroud 12. As shown in FIG. 1, the dimensions of the retaining holes 24, 26 and/or the retaining pin 22 may be designed such that a radially outer end 30 of the retaining pin 22 is recessed relative to an outer surface 28 of the turbine casing 10 when the pin 22 is inserted into the retaining holes 24, 26. Additionally, a threaded opening 32 may be defined in the radially outer end 30 of the retaining pin 22.
It should be appreciated that, in one embodiment, the retaining holes 24 defined in the turbine casing 10 may include a counter-bore 34 configured to receive a portion of a plug (not shown) for plugging the retaining holes 24 during operation of the gas turbine.
During downtimes, it is often necessary to remove the retaining pins 22 from the turbine casing 10 to allow removal of the turbine shroud 12 and/or to permit other maintenance operations to be performed on the gas turbine. However, due to improper installation of the retaining pins 22 and/or wear and tear occurring during turbine operation, removal of the retaining pins 22 can be a very time and labor intensive process. For instance, the retaining pins 22 are often bent during installation and/or become damaged as a result of vibrations and/or relative movement occurring between the turbine casing 10 and the turbine shroud 12, thereby causing the retaining pins 22 to become stuck within the retaining holes 24, 26. Additionally, dirt and other debris may become trapped between the retaining pins 22 and the turbine casing 10 and/or the turbine shroud 10, thereby further increasing the difficulty of removing the pins 22.
Various methods are known for removing the retaining pins 22 from the turbine casing 10. However, it has been found that each of these conventional methods presents one or more disadvantages. For instance, one known method for removing the retaining pins 22 includes the use of small fasteners together with heavy-duty pliers. Specifically, a small fastener is typically screwed into the threaded opening 32 defined in each retaining pin 22. The pliers are then utilized to pull the fastener and retaining pin 22 out from the turbine casing 10. Another conventional method utilizes a slide-hammer-like device in order to transmit a radially outward force to the retaining pin 22. For instance, it is known to screw a threaded rod into the threaded opening 32 of a retaining pin 22 and attach a sliding weight onto the threaded rod to create a makeshift slide hammer that can be used to remove the retaining pins 22. However, due to the inconsistent nature of the force applied by these conventional methods and/or due to the design limitations built into the retaining pins 22, the fasteners and/or threaded rods used with these methods are prone to fatigue failure at the edge of the threaded openings 32 during the removal process. When this occurs, it is typically necessary to drill out the retaining pins 22 using suitable machining equipment, thereby further increasing the time and labor required to remove the pins 22.
Accordingly, a tool that can be used to quickly, easily and/or consistently remove retaining pins from a turbine casing would be welcomed in the technology.